We shall continue to explore the host and parasite factors relevant to the pathogenesis of schistosomiasis and of granuloma formation with added emphasis on the immune effector functions of granuloma macrophages. Pure macrophage populations ranging from monocytes to epithelioid cells and giant cells have been obtained from murine schistosome granulomas and will be further fractionated and characterized in vitro as to their differences in behavior, biochemical and immunological markers. In addition to comparisons of cell surface receptors, phagocytic potential, enzymatic and secretory activities by established methods, we shall focus on specific surface binding, endocytosis, and catabolism of schistosome egg antigen, and shall seek evidence that schistosome granuloma macrophages are better equippped for these tasks than other mononuclear phagocytes. We shall attempt to define the specialized effector functions of epithelioid cells and pursue the possibility of a "distribution of labor" between granuloma macrophages. In this pursuit, we shall analyze the effects of variant host immune status (T-cell deprived versus unaltered versus immunopotentiated; acutely versus chronically infected) and of variant nidus composition (S. mansoni versus S. japonicum versus S. mekongi) on macrophage morphology and activity. To analyze the macrophage activities and/or vascular events related to central granuloma necrosis, we shall compare glucan potentiated versus unpotentiated S. mansoni granulomas. This research is responsive to the priorities established by a 1980 NIAID-NHLBI Granuloma Workshop and is relevant to a better understanding of endemic schistosomiasis, as well as of other chronic granulomatous infections of humans and animals.